S O U R C E

CONSTRUCT SOLUTION OPTIONS

The goals of an effective porcine reproductive and respiratory syndrome (PRRS) control strategy should be to:

  • prevent new PRRS virus introduction
  • reduce virus spread
  • minimize severity and economic impact

PRRS control is much more than just vaccination alone. It requires a systematic approach to PRRS management to achieve long-term success.

PREVENT INFECTION – Eliminate introduction of new PRRS virus by establishing the strongest possible biosecurity and pig flow management.

MAXIMIZE IMMUNITY – Establish and maintain uniform immunity in the whole herd

MINIMIZE TRANSMISSION/EXPOSURE – Reduce circulation of resident virus using a PRRS control program tailored to the needs of each farm, which includes biosecurity, pig flow management and immunity management.

  • BREEDING HERD
    CONTROL
    ELIMINATE
    PREVENT

    To control PRRS in the breeding herd, a possible solution would be:

    Load-Close-Expose protocol

    1. Load the farm with replacement gilts — enough inventory to maintain closure
    2. Close the farm for as long as possible, preferably 200+ days
    3. Expose the breeding herd via mass vaccination in order to generate uniform immunity throughout the breeding-herd population
    4. Reopen the herd only to gilts that have been vaccinated prior to introduction to the breeding herd, with the goal to be immune and non-infectious (via diagnostics – ELISA-positive and PCR-negative) at entry to breeding herd when reopened
    5. Perform quarterly mass vaccination of sow herd to maintain stability
    6. Monitor your PRRS status through diagnostics in order to confirm stability

    Studies show benefits of using vaccination to achieve PRRS stability in a load-close-expose protocol — learn more here.

    Work closely with your herd veterinarian to diagnose PRRS and determine the right course of action for your operation.

    Once you have controlled the spread of wild-type PRRS virus, there are several possible options for eliminating the virus from your herd.

    Option A – Conduct a “Depop/Repop”

    1. Remove entire pig population from the site
    2. Clean/disinfect/dry (Decontaminate environment.)
    3. Repopulate with naïve/PRRS-negative animals
    4. Monitor your PRRS status through diagnostics in order to maintain/confirm PRRS-negative status

    Option B – Load-Close-Expose

    1. Load the farm with replacement gilts — enough inventory to maintain closure
    2. Close the farm for as long as possible, preferably 200+ days
    3. Expose the breeding herd via mass vaccination in order to generate uniform immunity throughout the breeding-herd population
    4. Reopen the herd only to gilts that have been vaccinated prior to introduction to the breeding herd, with the goal to be immune and non-infectious (via diagnostics — ELISA-positive and PCR-negative) at entry to breeding herd when reopened
    5. Perform quarterly mass vaccination of sow herd to maintain stability
    6. Monitor your PRRS status through diagnostics in order to confirm stability

    Option C – Herd closure alone

    1. Close the farm for as long as it takes to generate uniform population immunity and non-infectious status (as measured by diagnostics); length of closure is variable due to many factors (e.g., farm size, virus strain)
    2. This protocol depends on using wild-type virus circulation/infection to build natural immunity – there is no vaccine used and there can be no new entries to the farm
    3. Wild-type virus will die out and be cleared from the population
    4. Move positive animals out and negative animals in

    Note: Herd closure alone (Option C) typically takes longer to build uniform immunity than through a load-close-expose approach (Option B).

    Once you have eliminated the PRRS virus from your operation, take steps to prevent virus introduction/re-introduction.

    1. Completely eliminate PRRS virus via depop/repop,
      load-close-expose or herd closure – the herd must be naïve/PRRS-negative
    2. Ongoing repopulation with naïve/PRRS-negative animals only
    3. Monitor your PRRS status through diagnostics in order to confirm PRRS-negative status

    Work closely with your herd veterinarian to diagnose PRRS, and determine the right course of action for your operation.

  • Growing pigs
    CONTROL
    ELIMINATE
    PREVENT

    In situations where there is circulating PRRS virus or risk of virus exposure is high in growing pigs, the most common goal is to control the PRRS virus. Best approaches include:

    1. Conduct partial depopulation, removing positive animals
    2. Improve health and performance of pigs
    3. Use vaccination to maximize immunity

      For optimum protection, pigs should be vaccinated at least three to four weeks prior to PRRS virus exposure. In most cases, vaccine can be used at or around weaning to provide protection against infection all the way to market. Work with your veterinarian to understand and determine optimum vaccination timing.

    4. Implement a biosecurity plan to minimize virus introduction/reintroduction and transmission
    5. Manage your pig flow to reduce interaction with
      PRRS–positive pigs

      It is recommended to use all-in/all-out by barn (or preferably by site)

    Work closely with your herd veterinarian to diagnose PRRS, and determine the right course of action for your operation.

    In rare occasions, growing pig operations can eliminate PRRS exposure. These operations tend to be in low pig-dense areas with a low risk for virus introduction/re-introduction. Potential options to achieve PRRS virus elimination include:

    1. Conduct depop/repop
    2. Implement vaccination protocol with strategic pig flow.
      • Example
        • Vaccinate twice — 30 days apart — and close farm for at least eight weeks
        • Empty PRRS-positive barns and replace with PRRS-negative animals
        • Conduct strict biosecurity between PRRS-negative and PRRS-positive barns until entire farm achieves PRRS-negative status
    3. Monitor your PRRS status through diagnostics in order to confirm PRRS–negative status

    Work closely with your herd veterinarian to diagnose PRRS, and determine the right course of action for your operation.

    There may be operations in low pig-dense areas who have either successfully eliminated the PRRS virus or have never been exposed. In these cases, it is important to prevent introduction or re-introduction of the virus.

    1. Completely eliminate PRRS virus via depop/repop,
      load-close-expose or herd closure; the herd must be naïve/PRRS-negative
    2. Ongoing repopulation with naïve/PRRS-negative animals only
    3. Monitor your PRRS status through diagnostics in order to confirm PRRS-negative status

    Work closely with your herd veterinarian to diagnose PRRS, and determine the right course of action for your operation.